Combined propulsion cuts maritime fuel consumption

An innovative marine propulsion system combining three technologies into one enables cutting emissions and consumption of fuel by up to 10 per cent.

The TRIPOD project, coordinated by the VTT Technical Research Centre of Finland is trying to integrate three separate propulsion technologies – the RudderPod units, CLT propellers and CRP propulsion – into a single system.

As all of these subsystems are known for their high efficiency, the team hopes to achieve unprecedented parameters.

Fuel saving for a single cargo ship could amount up to half million Euros, improving the efficiency of newly built systems by 10 per cent and that of retrofitted engines by 5 per cent. Equivalent annual fuel savings for a single large container ship would be 0.5 to one million Euros

The team suggests a more flexible positioning of the electric RudderPod unit at the ship stern, independently of the location of the main engine. The units could be located behind the main propeller working as the aft-propeller of a CRP unit. The rotational speed of the Rudderpod propeller can also be adjusted, improving the propeller's efficiency and mitigating propeller-induced noise and vibration.

The CLT propeller blades can be more loaded at the tip than those of conventional propellers, which results in an improvement of the propulsion efficiency.

In the CRP system, the contra-rotating aft propeller recovers rotational energy losses from the main propeller, improving overall efficiency.

The team is trying to assess the economic viability of the concept, performing cost benefit analysis for the operation of the reference ships. According to the results of the study, if the investment level can be brought down, ship-owners will be interested to explore further installation opportunities especially in new-building projects of large container ships.